1. Field of the invention
The present invention generally relates to a load-carrying vehicle and more particularly to a cross-country vehicle having a track drive as well as a likewise driving front steering wheel.
2. Background of the invention
The vehicle of the invention is intended for carrying light loads over rough and soggy grounds and is particularly adapted for works in wooded areas although it may also be used at various other places that are hard to reach by standard road vehicles. It is light in weight and low in height so that it can be controlled by an operator who can walk behind it or, if necessary where the ground is too rough or soggy, the operator may stand on a running-board provided at the rear of the vehicle or he may still stand in the load box or platform. Such a vehicle must be of sturdy construction while being inexpensive and safe in use. Its main feature is that it is driven by a track drive and a front wheel drive both simultaneously powered by a motor assembly located between the track and the front wheel so that its weight be applied mostly on the front wheel.
A prior art search was carried out before the filing of the present specification, which search has revealed the following U.S. Pat. Nos.:
2,493,613--1950--Bortnick PA1 2,770,310--1956--Gates PA1 3,295,622--1967--Pitchford PA1 3,789,941--1947--Robertson PA1 4,645,022--1987--Bergquist
The most pertinent document appears to be the PITCHFORD patent which discloses a load carrier actuated by a motor coupled to a speed reducer and located behind the load box or bucket. It is steered by twin wheels also situated behind the load box. A reverse action linkage assembly operatively connects the twin steering wheels and a pair of operating handles for pivoting the twin steering wheels in a direction reverse that of the pivoting of the operating handles so that the vehicle turns in a direction which is opposite to the thrust applied by the operator. Apart from the fact that the vehicle turns in a direction which is opposite to the direction applied by the driver, which is awkward, there is little leverage action possible with the type of reverse action linkage used and the relative short distance between the pair of steering handles and the two wheels. Added to this is the use of twins steering wheels, all of which render steering difficult particularly in rough or soggy grounds.
The BERGQUIST patent, on the other hand, relates to a double track drive platform truck but of which steering is obtained by a gear alternatively applying power drive to either one of the two track units in order to steer the vehicle in the desired direction.
As to the ROBERTSON patent, it likewise relates to a light transport vehicle using a twin track drive. Notable in this case however, is the absence of steering wheel or differential track movement, the vehicle being handled by a thrust bar.
The remaining patents have only a remote pertinence and need not be analyzed here.